Command pattern implementation for angular 2. Command used to encapsulate information which is needed to perform an action.

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npm install @ssv/ng2-command@0.2.0



CircleCI npm version

Command pattern implementation for angular. Command's are used to encapsulate information which is needed to perform an action.

Primary usage is to disable a button when an action is executing, or not in a valid state (e.g. busy, invalid), and also to show an activity progress while executing.

Quick links

Change logs | Project Repository


Get library via npm

npm install @ssv/ngx.command

Choose the version corresponding to your Angular version:

Angular library
10 2.x+
4 to 9 (non ivy) 1.x+


Register module

import { SsvCommandModule } from "@ssv/ngx.command";

  imports: [
export class AppModule {


In order to start working with Command, you need to create a new instance of it.

import { CommandDirective, Command, CommandAsync, ICommand } from "@ssv/ngx.command";

isValid$ = new BehaviorSubject(false);

// use `CommandAsync` when execute function returns an observable/promise OR else 3rd argument must be true.
saveCmd = new Command(() => this.save()), this.isValid$);

// using CommandAsync
saveCmd = new CommandAsync(() => Observable.timer(2000), this.isValid$);

// using ICommand interface
saveCmd: ICommand = new CommandAsync(() => Observable.timer(2000), this.isValid$);

Command Attribute (Directive)

Handles the command canExecute$, isExecuting and execute functions of the Command, in order to enable/disable, add/remove a cssClass while executing in order alter styling during execution (if desired) and execute when its enabled and clicked.

Generally used on a <button> as below.


<!-- simple usage -->
<button [ssvCommand]="saveCmd">Save</button>

<!-- using isExecuting + showing spinner -->
<button [ssvCommand]="saveCmd">
  <i *ngIf="saveCmd.isExecuting" class="ai-circled ai-indicator ai-dark-spin small"></i>

Usage with params

This is useful for collections (loops) or using multiple actions with different args. NOTE: This will share the isExecuting when used with multiple controls.

<!-- with single param -->
<button [ssvCommand]="saveCmd" [ssvCommandParams]="{id: 1}">Save</button>
  NOTE: if you have only 1 argument as an array, it should be enclosed within an array e.g. [['apple', 'banana']], 
  else it will spread and you will arg1: "apple", arg2: "banana"

 <!-- with multi params -->
<button [ssvCommand]="saveCmd" [ssvCommandParams]="[{id: 1}, 'hello', hero]">Save</button>

Usage with command creator

This is useful for collections (loops) or using multiple actions with different args, whilst not sharing isExecuting.

<button [ssvCommand]="{host: this, execute: removeHero$, canExecute: isValid$, params: [hero, 1337, 'xx']}">Remove</button>
canExecute with params
<button [ssvCommand]="{host: this, execute: removeHero$, canExecute: canRemoveHero$, params: [hero, 1337, 'xx']}">Remove</button>
canRemoveHero$(hero: Hero, id: number, param2): Observable<boolean> {
  return of(id).pipe(
    map(x => x === "invulnerable")

Usage without Attribute

It can also be used as below without the command attribute.


CommandRef Attribute (directive)

Command creator ref, directive which allows creating Command in the template and associate it to a command (in order to share executions).

<div *ngFor="let hero of heroes">
  <div #actionCmd="ssvCommandRef" [ssvCommandRef]="{host: this, execute: removeHero$, canExecute: isValid$}" class="button-group">
    <button [ssvCommand]="actionCmd.command" [ssvCommandParams]="hero">
    <button [ssvCommand]="actionCmd.command" [ssvCommandParams]="hero">



In order to use with NgForm easily, you can use the following utility method. This will make canExecute respond to form.valid and for form.dirty - also can optionally disable validity or dirty.

import { CommandAsync, canExecuteFromNgForm } from "@ssv/ngx.command";

loginCmd = new CommandAsync(this.login.bind(this), canExecuteFromNgForm(this.form));

// options - disable dirty check
loginCmd = new CommandAsync(this.login.bind(this), canExecuteFromNgForm(this.form, {
  dirty: false


In order to configure globally, you can do so as following:

import { SsvCommandModule } from "@ssv/ngx.command";

    imports: [
        SsvCommandModule.forRoot({ executingCssClass: "is-busy" })

Getting Started

Setup Machine for Development

Install/setup the following:

  • NodeJS v10+
  • Visual Studio Code or similar code editor
  • TypeScript 3.1+
  • Git + SourceTree, SmartGit or similar (optional)
  • Ensure to install global NPM modules using the following:
npm install -g git gulp devtool

Project Setup

The following process need to be executed in order to get started.

npm install

Building the code

npm run build

Running the tests

npm test


Handles compiling of changes.

npm start

Running Continuous Tests

Spawns test runner and keep watching for changes.

npm run tdd

Preparation for Release

  • Update changelogs
  • bump version

Check out the release workflow guide in order to guide you creating a release and publishing it.